In the original fairy tale, Belle's mother is a fairy queen of a mortal king, and her foster mother is the recently-deceased wife of a gentleman-merchant and the mother of their three daughters in one version (in the original version (by Madame de Villeneuve) she's the mother of six sons and six daughters, or three sons and three daughters (see the abridged, rewritten version by Madame de Beaumont), which the 1991 film most-closely follows (minus any and all of Beauty's/Belle's siblings), later excluding the sons, leaving only Beauty/Belle and her two older sisters); and of which Beauty/Belle is always the youngest of all of them).
Her passing marked the beginning of a series of misfortunes that would befall her family before her youngest daughter, Beauty/Belle, willingly exchanged her own freedom for her father's life, and later brakes the curse that plagued the Beast.
In the original version by Madame de Villeneuve, Beauty/Belle was revealed to actually be a secret princess, the hidden daughter of the mortal King and fairy Queen of a kingdom called the "Fortunate Island", who, just shy of being 3-years-old, was switched by her fairy aunt for the ill and very young daughter of a merchant (who had just died in the care of her nurse), in order to protect her from the attempts on her life (by the same wicked fairy who would later place the curse upon the Beast/Prince for having spurned her advances), and passing her off as such for some 11/14-years to protect her before the truth is revealed. Beauty's/Belle's birth mother was a fairy who, having fallen in love with a mortal king and married him, but had kept it a secret from her fellow fairies because she was not yet of an age and rank amongst them to be allowed to do so.
When her secret was discovered, a majority number of fairies voted to imprison her, one of who was the same wicked fairy who would later curse the prince into a beast. Said same-wicked, older fairy, curious as to what charm the king had had to draw the younger fairy to him, becomes obsessed with him, assuming the identity of the young, widowed queen of a neighbouring country to seduce him; later, when this fails, she tries to kill-off the infant princess in order to pressure the king to taking her as his new wife under the pretext of him now needing to produce a new heir to his throne, but even after she'd believed she had succeeded with disposing of the infant Princess Beauty, was still refused by the king. Finally, Beauty is reunited with her birth father, and her mother is restored to them both, for having performed a dangerous service for the Fairy Queen of the Council of Fairies. The wicked fairy, her evil actions disclosed to the council, has now herself been de-powered and imprisoned by the fae council.
In Madame de Beaumont's version, the story is edited-down, shortened, simplified, and the secret princess subplot completely omitted; thus Beauty's/Belle's mother remains the late wife of the gentleman-merchant mentioned above.
Although Belle's mother was originally to have been mentioned in the 1989 version of the original screenplay of the film, she is the deceased mother of two daughters, Belle and Clarice, (this time with Belle as the oldest sister), and where-in after her death, her musicbox (the figurines on-which mirror those in the famous 18th-century painting "The Swing", by Jean Honore-Fragonard) is passed-down to Belle on her 17th birthday (said-musicbox being an heirloom that had been passed-down to Belle's mother on her own 17th birthday). But ultimately she was never brought up at all in the final edits of the 1991 original screenplay.
She is, however, mentioned in the song No Matter What, in Disney's musical adaptation, where Belle's father compares her to her late mother ("You are your mother's daughter; therefore you are class. ... creme de la creme"), hinting that Belle's mother might have originally been from the upper-classes of high society; possibly meaning further that Belle's mother was a daughter of a 'vieux riche' family, and who went on to marry a nouveau riche (Belle's father). Since Belle mentions that her family having not been from the Village originally ("Every morning just the same, since the morning that we came, to this poor provincial town"), it is a likely conclusion that Belle's mother had passed away before Belle and Maurice had moved to the village (depending upon just how much of Belle's backstory in the Disney film-&-musical matches that of it's namesake fairy tale).
Also, a portrait of her reading to a younger Belle can be seen on the wall inside the replica of Belle's cottage that is a part of the Enchanted Tales with Belle attraction at Magic Kingdom. In addition, she was also seen with the same book that Belle got from the bookseller, indicating that she was the reason why the book was her favorite.
She also appeared in the Once Upon a Time episode "Family Business", portrayed by Frances O'Connor. In this version, she was named Colette. She was killed by an Ogre on Ogre Wars while protecting her daughter.
Zoe Rainey has been cast to play her in the 2017 live-action adaptation.